From: Jens Axboe <axboe@kernel.dk>
To: Mike Snitzer <snitzer@redhat.com>
Cc: linux-block@vger.kernel.org, dm-devel@redhat.com, hch@lst.de,
ming.lei@redhat.com
Subject: Re: [dm-devel] [PATCH v6 2/2] dm: support bio polling
Date: Tue, 8 Mar 2022 18:02:50 -0700 [thread overview]
Message-ID: <eac88ad5-3274-389b-9d18-9b6aa16fcb98@kernel.dk> (raw)
In-Reply-To: <20220307185303.71201-3-snitzer@redhat.com>
On 3/7/22 11:53 AM, Mike Snitzer wrote:
> From: Ming Lei <ming.lei@redhat.com>
>
> Support bio(REQ_POLLED) polling in the following approach:
>
> 1) only support io polling on normal READ/WRITE, and other abnormal IOs
> still fallback to IRQ mode, so the target io is exactly inside the dm
> io.
>
> 2) hold one refcnt on io->io_count after submitting this dm bio with
> REQ_POLLED
>
> 3) support dm native bio splitting, any dm io instance associated with
> current bio will be added into one list which head is bio->bi_private
> which will be recovered before ending this bio
>
> 4) implement .poll_bio() callback, call bio_poll() on the single target
> bio inside the dm io which is retrieved via bio->bi_bio_drv_data; call
> dm_io_dec_pending() after the target io is done in .poll_bio()
>
> 5) enable QUEUE_FLAG_POLL if all underlying queues enable QUEUE_FLAG_POLL,
> which is based on Jeffle's previous patch.
It's not the prettiest thing in the world with the overlay on bi_private,
but at least it's nicely documented now.
I would encourage you to actually test this on fast storage, should make
a nice difference. I can run this on a gen2 optane, it's 10x the IOPS
of what it was tested on and should help better highlight where it
makes a difference.
If either of you would like that, then send me a fool proof recipe for
what should be setup so I have a poll capable dm device.
--
Jens Axboe
--
dm-devel mailing list
dm-devel@redhat.com
https://listman.redhat.com/mailman/listinfo/dm-devel
WARNING: multiple messages have this Message-ID (diff)
From: Jens Axboe <axboe@kernel.dk>
To: Mike Snitzer <snitzer@redhat.com>
Cc: ming.lei@redhat.com, hch@lst.de, dm-devel@redhat.com,
linux-block@vger.kernel.org
Subject: Re: [PATCH v6 2/2] dm: support bio polling
Date: Tue, 8 Mar 2022 18:02:50 -0700 [thread overview]
Message-ID: <eac88ad5-3274-389b-9d18-9b6aa16fcb98@kernel.dk> (raw)
In-Reply-To: <20220307185303.71201-3-snitzer@redhat.com>
On 3/7/22 11:53 AM, Mike Snitzer wrote:
> From: Ming Lei <ming.lei@redhat.com>
>
> Support bio(REQ_POLLED) polling in the following approach:
>
> 1) only support io polling on normal READ/WRITE, and other abnormal IOs
> still fallback to IRQ mode, so the target io is exactly inside the dm
> io.
>
> 2) hold one refcnt on io->io_count after submitting this dm bio with
> REQ_POLLED
>
> 3) support dm native bio splitting, any dm io instance associated with
> current bio will be added into one list which head is bio->bi_private
> which will be recovered before ending this bio
>
> 4) implement .poll_bio() callback, call bio_poll() on the single target
> bio inside the dm io which is retrieved via bio->bi_bio_drv_data; call
> dm_io_dec_pending() after the target io is done in .poll_bio()
>
> 5) enable QUEUE_FLAG_POLL if all underlying queues enable QUEUE_FLAG_POLL,
> which is based on Jeffle's previous patch.
It's not the prettiest thing in the world with the overlay on bi_private,
but at least it's nicely documented now.
I would encourage you to actually test this on fast storage, should make
a nice difference. I can run this on a gen2 optane, it's 10x the IOPS
of what it was tested on and should help better highlight where it
makes a difference.
If either of you would like that, then send me a fool proof recipe for
what should be setup so I have a poll capable dm device.
--
Jens Axboe
next prev parent reply other threads:[~2022-03-09 1:03 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-07 18:53 [PATCH v6 0/2] block/dm: support bio polling Mike Snitzer
2022-03-07 18:53 ` [dm-devel] " Mike Snitzer
2022-03-07 18:53 ` [dm-devel] [PATCH v6 1/2] block: add ->poll_bio to block_device_operations Mike Snitzer
2022-03-07 18:53 ` Mike Snitzer
2022-03-09 1:01 ` [dm-devel] " Jens Axboe
2022-03-09 1:01 ` Jens Axboe
2022-03-07 18:53 ` [PATCH v6 2/2] dm: support bio polling Mike Snitzer
2022-03-07 18:53 ` [dm-devel] " Mike Snitzer
2022-03-09 1:02 ` Jens Axboe [this message]
2022-03-09 1:02 ` Jens Axboe
2022-03-09 1:13 ` [dm-devel] " Ming Lei
2022-03-09 1:13 ` Ming Lei
2022-03-09 16:11 ` Jens Axboe
2022-03-09 16:11 ` [dm-devel] " Jens Axboe
2022-03-10 4:00 ` Ming Lei
2022-03-10 4:00 ` [dm-devel] " Ming Lei
2022-03-10 4:06 ` Jens Axboe
2022-03-10 4:06 ` [dm-devel] " Jens Axboe
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